Many welding methods for suppressing sputtering and carrying out stable welding have been proposed from the prior art in a gas shield arc welding using a consumable electrode.
In a method for controlling an arc welding device, the length of an arc generation period of one time is detected, an output voltage of a welding power supply in the next arc generation period is reduced proportional to the length of the detected arc generation period, and a welding current in the next arc generation period is increased inversely proportional to the length of the arc generation period of one time in an aim of enhancing the response speed and rapidly recovering the stable welding state is known. A technique described in Japanese Patent Publication No. 4028075 is related to such prior art.
In the conventional welding control method, however, the welding current (broken line portion of FIG. 4) for opening the short circuit during the welding often does not have the short circuit current waveform appropriate for the welding state since the increase rate thereof is constant every time, as with the waveforms of the welding current and the welding voltage illustrated in FIG. 4. Thus, the short circuit may not be normally opened and an abnormal short circuit may occur, and the welding may become unstable.
The sputtering may occur greatly by setting the increase rate of the short circuit current to a large value in advance taking into consideration the lack of heat input and the response to when the welding becomes unstable.